This is a prospective, open-label, single-dose, single-arm phase I-II study in which 15 patients diagnosed with gonarthrosis grade II-III (Kellgren and Lawrence) will enter the study with the primary objective of assessing the feasibility and safety of the knee articular infiltration of autologous bone marrow mesenchymal stem cells (MSC). Secondary objectives are to assess the efficacy by imaging procedures and clinical questionnaires.